Moving armature receiver assemblies with vibration suppression

Abstract

Moving armature receiver assemblies wherein a first U-shaped armature and a second U-shaped armature are configured for suppression of vibration of a housing structure along a longitudinal housing plane. The first and second U-shaped armatures may be shifted away from each other along a longitudinal housing plane to render the first and second U-shaped armatures partially overlapping in the orthogonal plane with a predetermined overlap distance.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a continuation-in-part of prior application Ser. No. 13 / 422,746, filed Mar. 16, 2012, now allowed, entitled “Moving Armature Receiver Assemblies with Vibration Suppression”, which claims the benefit of U.S. Provisional Ser. No. 61 / 454,759, filed Mar. 21, 2011, both of which are incorporated herein by reference in their entireties.FIELD OF THE INVENTION[0002]The present invention relates to moving armature receiver assemblies wherein a first U-shaped armature and a second U-shaped armature are configured for suppression of vibration of a housing structure along a longitudinal housing plane. The first and second U-shaped armatures may be shifted away from each other along a longitudinal housing plane to render the first and second U-shaped armatures partially overlapping in the orthogonal plane with a predetermined overlap distance.BACKGROUND OF THE INVENTION[0003]Moving armature receivers are widely used to convert elect...

AI Technical Summary

Benefits of technology

[0012]Another embodiment of the present moving armature receiver assembly suppresses mechanical vibration in direction of the longitudinal housing plane by rotating the first and second U-shaped armatures in opposite directions about the longitudinal housing plane. If the U-shaped armatures are rotated in such a way that the resulting force components acting on the vibrating deflectable legs of both U-shaped armatures lie on the same axis, but project in opposite direction, considerable suppression of the resulting force components is achieved.

[0016]In one embodiment of the invention, the deflectable leg of the first U-shaped armature and the deflectable leg of the second U-shaped armature project into a common magnet gap. The magnet gap may be formed between outer surfaces of a pair of oppositely positioned permanent magnets. The use of a common or shared magnet gap is advantageous for several reasons such as to minimize overall dimensions of the moving armature receiver assembly. Smaller dimensions are a significant advantage in hearing instrument applications and other size constrained applications. Furthermore, the common or shared magnet gap is also beneficial in reducing the number of separate components of a motor assembly or system of the moving armature receiver assembly. In addition, the number of manufacturing steps required to produce the moving armature receiver assembly may be reduced. Both of these latter factors are effective in reducing the total manufacturing costs of the moving armature receiver.

[0017]In one such embodiment, the first and second U-shaped armatures are positioned mirror symmetrically about the longitudinal housing plane extending in-between the first and second U-shaped armatures so as to orient the first and second U-shaped armatures in same direction along the longitudinal housing plane. This mirror symmetrical orientation of the U-shaped armatures means that the deflectable leg of the first U-shaped armature and the deflectable leg of the second U-shaped armature extend parallelly to each other in close proximity along the longitudinal housing plane for example separated by an air gap with a height between 2 and 20 μm, more preferably between 5 and 10 μm. Furthermore, the first and second curved linkage portions are similarly oriented along the longitudinal housing plane, i.e. the curved linkage portions “points” in the same direction. The mirror symmetrical orientation of the U-shaped armatures in connection with the shared magnet gap means that both deflectable legs are displaced simultaneously in the same direction perpendicular to the longitudinal housing plane, i.e. in a z-axis direction. Consequently, the first and second curved linkage portions are displaced in opposite directions along the longitudinal housing plane so as to suppress or attenuate mechanical vibration in the latter plane. One or both of the displaceable legs may be coupled to a diaphragm through a suitable drive pin or pins so that vibratory motion of the displaceable leg(s) are conveyed to the diaphragm for sound pressure generation. This embodiment can provide a moving armature receiver assembly with small height and small length due to a close proximity of the U-shaped armatures and their alignment below each other. While the vibration suppression in the z-axis direction may be less than the suppression obtainable in other embodiments of the present invention due to the simultaneous displacement of the deflectable legs in the same z-axis direction, an overall length of the first and second U-shaped armatures can be made very small. In addition, suppression of vibrational torque or rotational force components can also be effective because drive pins or rods, coupling the deflectable legs to a shared compliant diaphragm, can be placed in close proximity on the respective deflectable legs of the first and second U-shaped armatures.

[0019]In yet another embodiment of the present moving armature receiver assembly where the deflectable legs are arranged in the common magnet gap, dimensions of first and second U-shaped armatures are substantially identical. Furthermore, the deflectable leg of the first U-shaped armature is preferably coupled to a first compliant diaphragm and the deflectable leg of the second U-shaped armature coupled to a second compliant diaphragm. Effective vibration suppression of the housing structure along the longitudinal housing plane can be achieved by situating identically sized portions of the deflectable legs in the common magnet gap and use essentially identical mechanical and acoustical characteristics of the first and second compliant diaphragms. Furthermore, good vibration suppression of the housing structure is also achieved along the plane perpendicular to the longitudinal housing plane due to the substantially identical and oppositely directed vibration forces created by the oppositely directed displacement of the deflectable legs along the latter plane.

[0022]In another embodiment where the respective deflectable legs of the first and second U-shaped armatures are arranged in separate magnet gaps, the first magnet gap and the second magnet gap are aligned to each other along the longitudinal housing plane. In addition, the deflectable legs of the first and second U-shaped armatures are both positioned in the longitudinal housing plane, preferably centrally through a middle of each of the first and second magnet gaps. In this embodiment, motor assemblies of the moving armature receiver assembly, including the first and second U-shaped armatures, may be aligned along the longitudinal housing plane. The motor assemblies are preferably arranged within a common receiver housing to provide a compact receiver assembly with low height despite the use of separate magnet gaps for the first and second U-shaped armatures. An advantageous variant of this embodiment comprises a first drive rod coupling a distal end of the deflectable leg of the first U-shaped armature to a first diaphragm. A second drive rod is used for coupling a distal end of the deflectable leg of the second U-shaped armature to a second diaphragm. In this manner, the first and second drive rods may be located in close proximity horizontally (i.e. along the longitudinal housing plane) to provide good suppression of rotational vibration components.

[0026]In the above-mentioned embodiments, the deflectable legs of the first and second U-shaped armature are preferably configured for oppositely directed displacement along the z-axis plane so as to also suppress vibration of the receiver housing along the z-axis plane. This property may be achieved by selecting appropriate spatial orientation of the first and second U-shaped armatures and / or appropriate directions of the magnetic fields in the separate magnet gaps.

Problems solved by technology

These vibration components are undesirable in numerous applications such as hearing instruments or other personal communication devices where these vibrations may cause feedback oscillation due to the coupling of mechanical vibration from the housing of the moving armature receiver to a vibration sensitive microphone of the personal communication device.

However, these resilient suspensions exhibit relatively small compliance or large stiffness along a longitudinal housing plane of the receiver while exhibiting a much larger compliance in the housing planes transversal to the longitudinal housing plane.

Unfortunately, this type of mirror-symmetrical dual-receiver design is not very efficient in cancelling or attenuating mechanical vibrations along the central longitudinal plane of the receiver housing.

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